Removal of metallic obstructions in well borings by oxidation



L. H. WATKlNs 2,571,636 REMOVAL OF METALLIC OBSTRUCTIONS IN WELL BORINGS BY OXIDATION 2 SHEETS-SHEET l Oct. 16, 1951 Filed oct. 14, 1947 uri Oct. 16, 1951 L.. H. wATKlNs REMOVAL OF METALLIC OBSTRUCTIONS IN WELL BORINGS BY OXIDATION 2 SHEETS-SHEET 2 Filed oct. 14', 1947 I INVENTOR. 6W/'6 Wat/vins A fa/"f7 eye Patented Oct. 16, 1951 REMOVAL OF METALLIC OBSTRUCTIONS IN WELL BORINGS BY OXIDATION Lewis H. Watkins, Caracas, Venezuela Application October 14, 1947, Serial No. 779,724

Claims.

This invention relates to well drilling or oil well producing, and more particularly to an improved apparatus for removing metallic obstructions, such as lost tools, drill-stem sections, tubing, fishing tools, packers, plugs, casing, etc., from well borings of any depth, especially deep borings such as those drilled for oil, by oxidation.

In drilling wells, such as deep oil wells, it frequently happens that a drilling bit, or other tool becomes detached from the drill stem to remain as an obstruction ,within the well bore. The drill stem itself may twist oi and a section thus becomes lodged in the hole, defying mechanical means of being dislodged and brought to the surface,

Present-day fishing tools may themselves be lost in the hole after engaging the fish but unable to dislodge it. Joints or sections of casing often collapse, are torn from the main string, and become obstructions to further progress.

When any of these accidents occur, it becomes impossible to proceed with the normal drilling operation until the obstruction in question has been removed, or in some manner displaced from the bore of the well.

In conventional drilling practice, failure to remove (or by-pass) the obstruction may result in the abandonment of the well. And as this may happen at a depth of several thousand feet below the surface of the ground, such an abandonment entails a substantial financial loss and large waste of time, labor, etc. Loss of production alone may amount to huge sums.

The fact that the obstructing body in the well bore may be at great depth increases the diculty and time necessary to engage the object with a mechanical fishing tool, or otherwise dislodging or removing it.

It is among the objects of the present invention to provide suitable apparatus for removing the obstructing metallic body, or bodies from well borings by burning such bodies, that is, consuming the body by oxidation to substantially complete destruction, and to fuse or vaporize the obstruction inside the well bore, whether cased or open, and while submerged in iluid mud or water at the bottom of the bore, which method is eiective to quickly and completely destroy any kind of metallic obstruction in a well bore, is relatively inexpensive when compared with the present practice of mechanically shing for such an obstruction, and which 'can be performed by use of conventional well-drilling equipment and a simplied unit of special apparatus which may ce lowered through the well bore to the location of the obstruction.

A further object resides in the provision of an improved apparatus which employs the method for destructively removing a metal body obstructing a well bore which comprises raising the temperature of such a body to the oxygen ignition temperature of the metal of which it is formed and subjecting the body so heated to an oxidizing atmosphere until destruction thereof by burning is substantially completed.

Other objects and advantages will become apparent from a consideration of the following description in conjunction with the accompanying drawings, wherein:

Figure 1 is a diagrammatic longitudinal crosssection of a well bore, such as the bore of an oil Well, showing a metallic obstructing body in the bore and apparatus illustrative of the invention positioned to remove the obstructing body from the well bore;

Figure 2 is a longitudinal cross-section on a somewhat enlarged scale of the fragmentary upper-end portion of the apparatus illustrated in Figure 1;

Figure 3 is a plan View of the lower end of the apparatus;

Figure 4 is a diagrammatic view similar to Figure 1 showing in longitudinal elevation a modified form of apparatus especially equipped for operation while submerged in fluid to a great depth, portions being broken away to better illustrate the construction thereof;

Figure 5 is a longitudinal cross-section of the fragmentary upper end portion of the apparatus shown in Figure 4;

Figure 6 is a bottom plan viewof the apparatus shown in Figure 4; and

Figure '7 is afragmentary longitudinal `crosssection similar to Figure 5 showing a still further modified form of apparatus.

With continued reference to the drawings, there is diagrammatically illustrated a vertical well bore, generally indicated at I 0, into which is inserted a conventional tubular casing I l. The

drawings illustrate a conventional boring tool or bit I2 as having become detached from the tool stem and lost in the bottom of the bore. It is to be understood, however, that such a boring tool in the bottom of the well bore represents only one type of obstruction. Various other mechanical devices may be lost in the well bore and may become lodged at various positions longitudinally of the bore. For example, the tool stem itself may break and assume a twisted or inclined position in the bore from which it is impossible to dislodge it by mechanical means. An entirely diierent type of boring bit may be lost and of nely divided aluminum and` an'i oxide; of? a.A

metal of lower chemical activity thanaluminurn, such as iron oxide. These ingredients may be mixed in various proportions and may be cornbined with other componentslas may' b'er found? necessary or desirable. The principal requirement of the combustible mixture I4 in the'container I3 is that it burns ata temperature sufcientto' heat thei obstructingbody I2 tb a temperature atwhichthe -metal of the bodyl will i ignite and burn in an oxidizing atmosphere.`

A conventional time fu'sejy I 51 is secured in the: bottom Walll of' container I3' andmay be setto ignitethemixture'. I4 in the container at'anyndesired time interval afterA the` setting' of)l theA fuse;

This fuse may be of` any desired: construction and arrangementto performf the indicated function; but" aconventional. artillery fuse has been found to give entirely'satisfactoryresults;

Thev container I3, together with the fuse I5', and the4 mixture I4 filling the container constitute an incendiary bomb which,. when ignited and brought' substantially into contact'with the obstructing body' I2',. will heat' the bodyY I2 to the desired high temperature'andcause' the body to burn or decompose'.

In the arrangementillustrated, a secondicontainer. |61 is-di'sposed.imm`ediately above the'container. |31. and. preferably has its bottom end' secured'to the upper end of' the lowercontainer: I3. The container IB- contains a suitable flux mixture IIwhich may be a mixture of limestone andiron.ilings or. any materialv or combination of materials which willpromote theb'u'rning. of, the-metallic body lf2 o'nce` burning thereof hasr been started byA the actionof the mixture I4.in container I3.

A third cylindrical container I8V is disposed immediately above the container IlV and pref-- erably' has its" bottom end secured. to the. top

end of the intermediate container. I6.

While the ux container I6 has been illustrated as disposed in operative positionbetweenthe-incendiaryV bomband the container I8,` it maybe' disposed insome'other position, if desired, or may be entirely'omitted-in'anyfparticular instance in whichy itsy presence is-A not required.

The container` I8-, as illustrated, is hollow and' adapted to.- contain oxygen under pressure. This container may be made as long as desiredtocont'ain a suficient quantity of. oxygen for the complete combustion of an obstructing body, thetotallength' `of the three containers I3, I6 and:

Ilifbeingilimited'onlybythe capacity of the conventionalwell' derrick by means of which the apparatus' is' lowered in.` the well bore.

A" conventional gas valve' I 9`. is provided at' thev top-of'the'conta'iner I8 and'has a threaded fittingY 2li'to which a tube may be connected'i for intro.- ducing oxygen under pressure into the container. Thev valve is controlled by a conventional handwheel or similar device 2 I', andlis provided-'With a' pressure gauge v22`byfmeans of which the pressure'.

of the gas in the container may be observed at any time.

An internally screw-threaded cylindrical collar 23 is threaded onto the upper end of the container I8 and a dome-shaped cap or plug 24 is threaded into the projecting upper end of the collar. This plug has cut-away portions 25 providing windowsthrough which the., valve I9 may be'v operated and throughf which the gauge 22 may be observed, and has securedto its upper or.V dome end an extension 26 having its upper end formed to provide an externally screwthreaded conical pin 211, or tool-joint, to which is` secured the= lower end of a cylindrical cable box. 28.*which; receives the lower end of cable 29therein for suspending the entire apparatus fromthecable. The cable may be secured in theA cable box by conventional means, such as by embedding the end of. the cable within the box in babbitt 'or similarrmetal.

A pluralityof tubularr conduits 30extend'downwardly fromv the' lowerv end ofl the; oxygen'y container I8" and through the bottom' Wall* of" the" bomb I3 with their'lower end'spositioned around the fuse I5, as is clearly. illustratedv in Figure- 3. These tubular. conduits: have their lower ends plugged or sealed by a suitable fusible material` so that oxygen cannot escapethrough them until the plugs are fused-after ignitionpf thebomb I3'.

Inv carrying out the improved method, after a metal toer or part, such asilthe bnn lzyhas been' lost. in the. well bore, the remaining. part of.' the tool stem,.and' other, structure stilll attachedj to the hoisting mechanism ofthe derrick is removed. from. the bore.

The apparatus, including` .the bomb.4 I3, the.

oxygen tank- I8, and, if.v desired,y thef ux con-- tainer- IB, is thensecuredto the. endof ahoisting. cable andsuspended-abovethetop-of the well as. aunit, the oxygen containery being i'llled` with oxygen: tothe desired pressure. The fuse- I5. isv

then set to ignite the. material I4'- inv the, bomb.

after a desired: time interval. suflicient. for lower,- ing the apparatus to the point of, obstructioninthewell bore;` The. apparat-us. isfthen loweredin the well bore until thelower. endfof. the bombis in contact. with or is at the location of.. theobstruction and is-held` in thisposition. until the fuse acts to ignite the combustible material inl the bomb. Upon ignitiomthisrmaterial burnsat an exceedingly` high temperature, temperatures of from 3800 to 4200 degrees centigrade being usual for such materials. Thisexceedingly high temperature heats the. obstructingv body. to a emperature at whichthe metal of the body will burn in oxidizing atmosphere, and may even reduce the body to a molten condition. The quantity of-material usedwill be dependent upon the amount necessary to. heat the body to the. desired. temperature, butxitv isI notl necessary to attempt to` destroy the obstructing body by merely the application thereto of the heat generatedby the. combustible material.- The burning of the material in the bombv will fuse the plugs or seals in thelower ends of the oxygen conduits 30 and immediately oxygen, under pressure, from the tank I8- willow through these tubes and. envelope the obstructing body, imping. ing upon itand producing an oxidizing atmosphere around it, so that thebody begins-to actively burn in the oxidized atmosphere. The containers I5, I6 and I8 havea-diameter less than the diameter of the' well bore, such-aste provide an annular space'3l through fwhichthe products of combustion of the obstructing body canpass upwardly through the bore and the body will thus be removed mainly in the form of gaseous products of combustion, any cinder or ash residue being easily displaced by the drilling tools when reinser-ted in the bore.

A deep oil well bore normally contains a column of iluid mud 3| in the lower portion thereof and it is thus necessary that the destructive action of the obstruction-destroying apparatus take place while the apparatus is submerged in this column of mud. This is accomplished by supplying all of the necessary oxygen to complete the destruction of the obstructing body to the body, so that the burning of the body will be carried out even though the location is submerged.

If the weight per volume of the apparatus is insufficient to cause it to sink through the mud with suilicient rapidity,4 additional weight can be added by securing one or more lengths 32 of drill stem between the plug 24 and the cable 29. As this drill stem is quite heavy, a few lengths or sections will be sufcient to force the apparatus down through the column of mud at the desired rate.

As the pressure of the fluid column at or near the bottom of a deep well is very high, several thousand pounds to the square inch being not uncommon, it is necessary when operating under such conditions to force the oxygen from the oxygen container against this outside pressure. While this might be accomplished in several ways, as by using an explosive charge in the oxygen container or a differential area piston subjectedlto the external pressure, simpliiied and eiective means for accomplishing this result are illustrated in Figures 4, 5, 6 and 7.

In the arrangement shown in Figures 4, 5 and 6, the domed plug 24 of Figure 1 is omitted and an outer end plug 33 is threaded into the outer end of collar 23. This plug has a central aperture which receives a piston rod 34. The aperture is surrounded by an internally screwthreaded boss 35 into which is threaded a packing gland 36 which compresses packing 31 around piston rod 34.

An inner end plug 38 is threaded into the collar into contact with lthe adjacent end of oxygen container I8 and is also provided with a central aperture receiving the piston rod 34. The joint between inner plug 38 and the piston rod may also be packed, if desired.

A piston 39 is disposed in the upper end of container I8 and provided with a central aperture receiving a reduced end portion 40' of piston r-od 34. Piston rod end portion 48 is externally screw threaded to receive a nut 4I and lock nut 42 which clamp the piston between the nut and annular shoulder 43 at the inner end of reduced extension 48 so that the piston is immovable relative to the piston rod. A packing 44 seated in an annular groove in the piston provides a fluid or gas seal between the piston and container I8.

Since the hollow plug 24 is eliminated and the upper end of container I 8 isv not available for mounting the valve I9 and pressure gauge 22, the valve may be connected to the lower end of one of the tubes 30 and the pressure gauge to another of these tubes, as shown in Figure 4. Although when in this position, the valve and gauge will be destroyed upon ignition of bomb I3, this is of no important consequence and does not affect the operation of the apparatus.

In order to force piston 39 down in container I8 after ignition of the bomb and thereby expel than in the arrangement described above.

the oxygen from the container I8 through tubesl 38 a suitable weight is applied to the upper end of piston rod 34. This weight may be applied by attaching the lower end of a tool stem section 21 to the upper end of the piston rod and permitting the weight of the section to bear on the rod. Each such section is very heavy and a number of sections may be applied in end-toend relationship as may be necessary to develop the necessary force on the piston to drive the oxygen out of the oxygen container, or by impact of the assembly.

Figure 7 illustrates an arrangement whereby a sucient oxygen expelling force may be applied to the piston with the use of lessI weight By the use of the modified arrangement of Figure 7 the desired result may be accomplished with `the use of only one or two drill stem sections regardl less of the height of the fluid column in the well and the iluid pressure at the location of the obstruction.

In this arrangement, a conventional shear relief valve 45 having a shear pin 46 of predetermined resistance to shear is extended through end plugs 33 -and 38 from the exterior of the container above outer plug 33 to the space between inner plug 38 and piston 39. When the container reaches a depth in the well bore at which the fluid pressure reaches the value for which the shear relief valve is set, the valve opens and admits the external fluid pressure to the top of piston 34 to assist the tool stem sections attached to the piston rod in forcing the piston down in the oxygen container to expel the oxygen therefrom.

A second shear relief valve is shown also extending through plugs 33 and 38. This is merely a duplicate valve to insure operation of the device in the event of the failure of one of the shear relief valves to open.

It is probable that most of the containers I3 and I6 will be consumed during the burning of the body I2. Any unburned portion of the apparatus, however, will adhere to the cable 29 and may be withdrawn from the well bore when the burning operation is completed.

If it is found that a single unit of apparatus is not suicient to completely destroy the obstructing body, as might be the case if a considerable length of tool stem were lost in the bore, the obstruction-destroying operation can be repeated until the obstructing body is entirely destroyed and no longer causes any obstruction to continue drilling of the bore.

The invention may be embodied in other specic forms without departing from the spirit or essential characteristics thereof. VThe present embodiment is, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being`indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are, therefore, intended to be embraced therein.

What is claimed is:

1. An apparatus for destructively removing an obstructing metallic body from a well bore comprising a container movable through said bore and containing a body of incendiary composition which, when ignited, is capable of generating heat at a temperature destructive to said obstructing body, means carried by the container for igniting the composition, an oxygen container mounted" onsaid iirstf container and disposedv thereabove; tubes depending from the' oxygen container and disposed in communicatonfthereandi containing abody of incendiary composition. capable, when ignited, of generating heat ata temperature destructive tosaid obstructing body, a settable ingiter carried bysaid container in operativeassociation with said body of' incendiary composition for igniting they latter, an oxygen' container secured to said first container and positioned thereabove when said apparatus is` in a well bore, tubes extending from said oxygen container in communication therewith and extending through the first container, saidtubes having: free terminals positioned below the first container, fusible closures in the free terminals of said' tubes, said closures being fused by heat of the initial ignition of the incendiary composition: to` open saidtubes' and permitA oxygen escaping from thef container to envelopeA the obst'mctingbody and produce an oxidizing atmosphere around it.

3'. An apparatusfor destructivelyremoving an' obstructing metallic body from a well borel comprising a container movable through said" bore and containing. a body of' incendiary composition capable, when ignited, of' generating heat at a temperature destructive to saidobstructing body, al setta'bl'e` igniter carried by said container in operative association with said bodyof'incendiary composition for igniting the latter, an oxygen container securedV to said'iirst container and positioned thereabove when said apparatus is in-a well bore, tubes extending from said oxygen container in communication therewith and' extending through the first container, saidV tubes havingV free terminals positioned below the first container, fusible closures in the free terminals of-Vsaid tubes, said closures 1being` fused by the heat of initial ignition of the incendiary compositionl to open saidtubes-and permit oxygen escaping from the container t0 envelope the obstructing body and' produce an oxidizing atmosphere around it, and means in saidoxygen container for forcing oxygen therefrom through the tubes against the pressure of a column of fluid in said well bore, said meansv comprising a piston slidably mounted in the upper end' of said oxygen container, a piston rod'connected to the piston, a; topendiplate for said oxygen container formed for sealing engagement around the piston rod which` passes slidably therethrough, and means extendingto thetop of the well bore for actuating` said piston rod to effect-a downstroke of the piston.

4. An apparatus for destructively removing an obstructing metallic body from a well bore comprising a container movable through said bore and containing a body of incendiary composition capable, when ignited, of generating heat. at a temperature destructive to said obstructing body, a settable igniter carried by said container in operativeassociation with said body of incendiary composition for igniting the latter, an oxygen container secured tol said first container and positioned thereabove when said apparatus is` in a well bore, tubes extending from said oxygen container in communication therewith and extending through the rst container, said tubes having free terminalspositioned below the first container, fusible closures in the free terminals of said tubes, said closures being fused by the heat of initial ignition of the incendiary composition to openA the tubes and permit oxygen escaping from the container to envelope the obstructing body and produce an oxidizing atmosphere around it, means in said oxygen container for forcing oxygen therefrom through the tubes against the pressure of a column of fluid in said Well bore, said means comprising a piston slidably mounted in the upper end of said oxygen container, -a piston rod connected to said piston, a top end plate for said oxygen container formed for sealing engagement around the piston rod which slidably passes therethrough, means extending to the top of the well bore for actuating said piston rod to effect a downstroke of the piston, and a shear relief valve extending through said top plate operative to admit iiuid pressure from the well bore into the oxygen container to act on the top surface of said piston when fluid pressure in said bore reaches a predetermined Value to assist said actuating means in forcing said piston downwardly in the oxygen container.

5. In an apparatus for destructively removing an obstructing metallic body from a well bore, a container movable through said bore and containing a body of incendiary composition capable. when ignited, of generating heat at a temperature destructive to said obstructing body, initial ignitingv means carried by said container, an oxygen container overlying the first container, tubes carried by the oxygen container in communication therewith and extending, when the apparatus is operatively disposed in a well bore, to a point below the rst container and fusible olosures in said lower ends of the tubes, said closures being fused by the heat of initial ignition of the incendiary composition to open the tubes and permit oxygen escaping from the container to engulf the obstructing body and produce an oxidizing atmosphere around it, a piston slidably mounted in the oxygen container for forcing the oxygen through the tubes, means extending tothe top of the well bore for actuating said piston and valve means carried by said container operative to admit fluid pressure from the well bore into the oxygen container to act on the top surface of said piston when fluid pressure in said bore reachesv a predetermined valueto assist said' actuating means in forcing the piston downwardly inthe oxygen container.

LEWIS H. WATKINS.

REFERENCES CITED Thefrfollowlng references are of record in the lel: of this' patent:V

UNITED STATES PATENTS Number Name Date 1,198,566 Monroe Sept. 19, 1916 1,510,926 De-Kaiser etal Oct. 7, 1924 2,076,308 Wells Apr. 6, 1937 2,286,192 Aitchisonl et al. June 16, 1942 2,436,036: Defenbaugh Feb. 17; 1948 

